Basic requirements on equipment with mutually interacting spiral teeth comprise either a change of a medium volume without or with a simultaneous increase of its pressure, or a change of pressure and/or flow rate at the output while maintaining the medium volume or an utilisation of a medium pressure energy without a change of the medium volume and conversion of the energy into a rotary motion or an utilisation of the pressure energy by simultaneous medium expansion and conversion of the energy on a rotary motion or expansion of a burning mixture of fuel and compressed medium volume and conversion of the pressure energy into a rotary motion by a simultaneous medium volume expansion.
There exist a plenty of well-known equipment operating on a principle of mutual interaction of spiral teeth wound-up on at least two rotors seating in a stator, or, as the case may be, wound-up on one rotor and on inner stator surface Spiral teeth surface can be by parts described by functions given in any point by three parameters, i.e. by a diameter of a basic helix, by an angle of an angular displacement and by an angle of a helix lead. Each rotor can be represented by a determined sum of profile sections running through co-axial rotating areas, usually defined as surfaces of second degree, namely a spherical surface, a conical surface and in limited values by a surface perpendicular to the axis of rotation. The solutions known at present have spiral teeth which are wound-up on a cylindrical or a conical shaft wrapper. These solutions are known for different type of profiles of spiral teeth, nevertheless they do not enable a variability and especially steepness of profile changes of the same spiral tooth along its axis. By rotors with a shaft cylindrical wrapper it is possible to change the thread intermediate space only by a change of spiral teeth lead. At rotors with a spiral conical wrapper it is possible to change the thread intermediate spaces by a change of spiral teeth lead and by a change of a vertex angle of the conical shaft wrapper. The change of volume of space between the threads is in both cases limited by the length and by rotors diameters. It is impossible to extremely increase the size of rotors because the demands on built-in space do not increase proportionally. Large masses can cause unbalances and oscillation of rotors and problems with their sealing.
Known equipment for media compressing, like rotational spiral compressors, work on a principle of rotors with cylindrical rotational wrapper and with spiral teeth having a constant lead and a constant teeth profile. These rotors function only by transporting a medium through thread intermediate spaces in the direction from input to output. The pressure is produced at the equipment output. The disadvantage comprise a limitation of a compression rate caused by equipment dimensions and by the construction as described above as well. The efficiency of the present equipment of this type is limited by a constant shape and size of labyrinth of the thread intermediate spaces.
The equipment with a constant volume of a thread intermediate space is also used as generators and in reversed arrangement as motors, e.g. pneumatic motors, hydro-motors, where a pressure medium is fed to an input and moves spiral rotors. The disadvantage comprise again an invariable and steep characteristics of a pressure change performed between the medium input and output.
By a serial arrangement of the equipment there is acquired a staggered increase of compression, while a parallel combination of a larger number of the equipment provides for an increase of the volume compression rate.
In principle as unsuccessful there can be depicted known constructions of internal combustion engines with spiral teeth. The arrangement of such motors has been so far restricted to combinations of two and more mutually interconnected individual equipment, like a compressor and an expander. The disadvantage of these solutions consist mainly in limited possibilities of adaptation of a shape of a working space and arrangement of individual parts of equipment for suction, compression, expansion and exhaustion to a particularly required procedure of an internal combustion process. All known equipment manifest large dimensions. The types with shafts and housing of a cylindrical shape have mainly large overall length and at the types with conical shafts and housing have large diameters. Such parameters negatively influence even a dynamic balancing of rotors.
Known equipment comprise for example a technical solution according to CZ utility model No. 8308, where spiral teeth are wound-up on a conical body and a rotating wrapper of rotors is also a conical one. In this type of equipment a change of a medium volume occurs already in a thread intermediate space, nevertheless process and degree of compression and expansion of a medium is limited by vertex angles of conical rotors. Such an embodiment cannot be modified so as to change a working characteristic of the equipment as required.
There is also known a solution of a combustion motor with a rotating disc as presented in CZ patent application PV 558-91, describing rotating compressor discs with thread surfaces splitting a working space of a rotating working disc. However this thread surfaces are not in a mutual interaction and the rotating compressor discs serve only as rotating slide valves of the working disc and do not transfer a pressure force into a torque. The disadvantages of this solution include a periodic charge cycle and maximum pressure impacts applied on rotating slide valves. The equipment requires perfect sealing. A wear of parts resulting from combined effects of mutually sliding movements and simultaneously acting impact forces will be high and therefore the service life of the equipment probably low.
Another similar solution of a rotating motor, included in a PCT patent application WO 93/14299, is an equipment utilising a rotating disc for splitting a working space of a rotor with a spiral tooth, the rotating disc being fitted with a notch allowing for a passage of the spiral tooth. The rotating disc and spiral tooth create two movable partitions of the working space. Outer convex surface of the working rotor is given by an outer shape of the rotating disc and do not determine working characteristics of the equipment. The rotating disc spiral tooth is not in interaction with any other spiral tooth.
Another known solution, as described in a paper DE 19738132 A1 is based on a principle of counter-rotating rotors with mutually adapted teeth profiles, with cylindrical or tapered rotation wrappers of rotors and with changing lead of spiral teeth of rotors. The compression happens already in the thread intermediate spaces, nevertheless the degree of compression is limited by the equipment dimensions. A transfer of a medium happens by a rotation of the rotors in mutually opposite directions, the medium being compressed only in an intermediate space of these rotors, not in a space between the rotor and the equipment housing. The construction allows only for a certain maximum possible length of the spiral teeth and a certain minimum number of threads of the spiral teeth is necessary to make it work.
Another known solution according to U.S. Pat. No. 5,533,887 has two interacting rotors running in mutually opposite directions. The two rotors seating in a common housing, have tapered shafts on which there are wound-up spiral teeth with a constant lead and rotational wrappers of the spiral teeth form have a shape of cones with an orientation opposite to that of the shafts. These rotation wrappers of the rotors define tapered inner spaces of the housing with which they are also in a mutual interaction. This construction provides for a surface sealing of the rotor spiral teeth against the housing and therefore the spiral teeth have identical lead depending on vertex angles of the tapered shafts and the housing, the angles determining a waveform of working characteristics of the equipment. By the same input parameters it is possible to obtain only corresponding output parameters. Thus an application variability of the equipment is significantly limited.
Another known design according to U.S. Pat. No. 2,908,226 provides only for skewed rotor axis and the same sense of spiral teeth lead and thus for the same sense of rotor rotation and a constant lead. Due to the constant teeth lead the teeth profile can be changed only by a design of the teeth side walls. To allow for a mutual rolling of the teeth, there is applied a recess in the teeth side wall, the recess being positioned in places where the profiles of adjacent teeth would overlap and prevent any rotation. The shape of rotor profiles thus results only from necessary basic mechanical requirements. The said design is a mere spiral conveyor with a compression of transported media.
There is also known a solution described in GB patent 419338. The equipment, a spiral pump or a compressor is furnished with teeth having only trapezoidal profile. Tooth height to width ratio equals approximately one. Rotors may be equipped with spiral teeth with only opposite sense of lead. Rotational wrapper of the rotors is of a cone shape only, or may comprise several cones with different vertex angles and with a staggered transition from one cone to the adjacent one. Therefore the teeth height and lead is changed only linearly. Only the two parameters are changed.
A solution according to GB patent 2 030 227 presents rotational compressor or a motor-generator powered by a pressurised media, the medium being preferably a gas. The design comprise two double spindles consisting of parts arranged into a spiral, the spindles of each pair being mirror-like arranged on a common shaft. The shafts may be only in a parallel arrangement. A rotational wrapper of the spindles has a conical shape and the spiral teeth have opposite lead with respect to the rotor symmetry plane. The equipment provides for a compression of a media from an input at one end towards a centre and expansion from the centre towards output on the other end. Outside diameter of spiral teeth is changed linearly, so the spindles are of a conical type and simultaneously there is changed only the teeth lead. The teeth profile can be adapted to the desired pressure input/output difference, but only a continuous change can be achieved.
A solution according to paper DE 197 28 434, suitable only for applications as a compressor or an air pump, may comprise only rotors with parallel axis and spiral teeth having opposite sense of lead. The construction provides for a change of a diameter and length of spiral teeth according to changing temperature to maintain clearance between rotors and a stator. Respective rotational wrapper of the rotors and stator inside surface are therefore defined only by one parameter, inside temperature.
Known constructions of mechanisms with spiral teeth of the above discussed type have been designed with respect to desired power at the output, mainly pressure or discharged volume as a final constant value. Only one or two dimension parameters have been selected as variables, while other dimensional parameters have become dependent values. Only in a case of possible limit value overrun, resulting from control calculations, there have been performed a correction and subsequent redesign of the mechanism shape. By a limited number of variables it is not possible to select a desired pressure distribution as a control parameter for design of shape and dimensions of the mechanism. None of the existing mechanisms provides for application of distribution of main parameters, namely pressure, volume and temperature, characterising state of a media in any part of a working space of the mechanism, as control functions for design of outside and/or inside shapes and dimensions of the mechanism. All so far known solutions allow for changes of profiles of spiral teeth and for changes of spiral teeth lead only in a restricted range. No particular exact requirements on media parameters like pressure, volume and velocity within inside working space can be applied.